Widen dropdown menu

I am trying to make the dropdown menu in the navigation bar a bit wider so text fits on one line. This is my site. http://www.hersheylibrary.org

I have searched the Modality support forum to find a CSS solution for my child theme and tried the CSS below increasing the width up to 500 px but neither CSS below seemed to work.

#nav ul ul a {
    width: 350px;
}

and also

#access ul ul a {
width: 350px;
}

If anybody knows how to help figure this out, I would be so happy! Thanks so much.